Hot water supplying apparatus

Abstract: The hot water supplying apparatus including a hot water generating section (1) having a flow generating path and a load section (2) having a load flow path with the flow generating path (3) and the load flow path (4) connected with a connection flow path and a circulating flow path having a circulation pump (7) therein being formed with these flow paths, in which heat exchangers (11) each having a heater (10) therein and a heat sensor (12) provided in the flow generating path (3) and controlling operations of the heaters (10) are provided in the hot water generating section (1), a temperature insulating/adjusting valve (13) is provided in the load path (4), a branch flow path connecting with the upstream side of the temperature insulating/adjusting valve (13) to the downstream side therefrom is provided in the load flow path (4), a load member (15) is provided in the branch flow path, and a bypath flow path (8) having a flow rate control valve (9) connecting with the upstream side from the heat exchanger to the downstream side therefrom is provided in the connection flow path (8).

Description: BACKGROUND OF THE INVENTION The present invention relates to a hot water supplying apparatus for houses, collective houses such as apartment houses, hotels, ordinary buildings, and other types of architecture having a number of living rooms therein such as plants. A known apparatus used for supplying hot water is shown in Fig. 7 and Fig. 8. This apparatus has a hot water generating section 1 and a load section 2 in which a flow generating path 3 and a load flow path 4 are formed respectively. An exit of the flow generating path 3 is connected to an entrance of the load flow path 4 by an outward flow path 5, and an exit of the load flow path 4 is connected to an entrance of the flow generating path 3 by an inward flow path 6 having a circulation pump 7 to form a circulating flow path with these flow paths. A water supplying path 27 having a valve 26 is connected to the inward flow path 6. In the hot water generating section 1 are provided a plurality of heat exchangers 11'-1,2,3 (3 units in this embodiment ) each having a heater 10 therein, and heat sensors 12-1,2,3 each provided downstream therefrom in the flow generating path 3 and controlling operations of the heater 10. In the load flow path 4 in the load section 2 is provided a temperature insulating/adjusting valve 13, the upstream and downstream sections thereof and a plurality of load members 15 (2 units in this embodiment) being connected by a branch flow path 14 with a calorimeter 16 provided in an inward flow section of the branch flow path 14. Fig. 8 shows details of a portion of the hot water generating section 1. Each heat exchanger 11'-1,2,3 of this section 1 has a heating can 18, in which are provided a high limit sensor 17, a water supply section 21 and a hollow and cylindrical heating chamber 19' arranged therein. A flame supply port 23 of the heater 10 comprising a burner is opened in a lower section of one side of the heating chamber 19' and an air exhaust port 24 is provided in the upper section of another side of said chamber. An air exhaust pipe 20 connected to this air exhaust port 24, and a heat exchanging section 22 of the outward flow path 5 are located at and in the upper section of the heating can 18. In the load member 15 are provided a hot water supplier 31, a warmer and other load equipment not shown herein respectively, while a clear water path 30 having a water cleaner 28 and a clear water pump 29 is connected to the inward flow path 6. In the conventional type of hot water supplying apparatus as described above, the temperature insulating/adjusting valve 13 is fully opened with the valve 26 opened to supply water via the water supply path 27 into the circulating flow path until the circulating flow path is filled with water, then the valve 26 is closed, the circulation pump 7 and the clean water pump 29 are actuated to circulate water inside said circulating flow path, and at the same time the heater 10 in each of the heat exchangers 11'-1,2,3 is actuated to start heating the water. When temperature of the water heated as described above reaches a specified level, the temperature insulating/adjusting valve 13 is once fully closed, and then the temperature insulating/adjusting valve 13 is opened to an opening degree so that temperature/pressure gauges 39, 40 located before and after the temperature insulating/adjusting valve 13 show a temperature and pressure difference and the temperature insulating/adjusting valve 13 indicates a preset minimum flow rate. This operation is required for the following reasons; as circulation of hot water is necessary even in no load condition where no hot water is consumed in a load member 15 of the load section 2, and as the length of the entire circulating flow path including flow paths in the hot water generating section 1 and the load section 2 is very large, if the circulation flow rate is too high, heat loss due to heat emission to outside of the pipe increases in proportion to the circulation flow rate. For this reason also heat loss due to heat emission by hot water flowing therein becomes larger, so that a flow rate of hot water flowing during no load condition must be suppressed to as low level as possible by way of prevention of heat loss. This operation is also required to generate a large pressure difference between the upstream side and the downstream side of the temperature insulating/adjusting valve 13 for the purpose to quickly supply hot water to the load member 15 in no load condition. If a hot water supply valve 35 connected to the hot water supplier 31 is opened and hot water is consumed, tap water is supplied from a water supply pipe 32 via a pressure switch 33, a signal from the pressure switch 33 is sent to a motor valve 34 for opening the latter, hot water is supplied to the hot water supplier 31, heat is exchanged instantly between this hot water and the supplied tap water, and hot water is supplied from the hot water supply valve 35. On the other hand, when the warmer is in service, the valve 36 is opened with hot water flowing thereinto, while when the warmer is not in service, the valve 36 is closed to prevent the hot water from flowing thereinto. The hot water used as described above passes through the calorimeter 16, and its heat value spent in the load section 2 is detected. A prescribed temperature level is fixed in each of the heat sensors 12-1,2,3. When the temperature of the water in the generating flow path 3 goes down to below the prescribed temperature, the heater 10 is actuated according to a signal from the heat sensors 12-1,2,3 to heat the water supplied from the water supply section 21 into the heat exchangers 11'-1,2,3, heat exchange is performed between this heated water and the water flowing in the heat exchange section 22 in the flow generating path 3, the water in this section 22 becoming hot. On the contrary, when the temperature of the water in the flow generating path 3 becomes higher than the prescribed level, operation of the heater 10 is stopped according to a signal from the high limit sensor 17, and heating the water supplied from the water supply section 21 into the heat exchangers 11'-1,2,3 is stopped. During these operations, the circulation pump 7 continues to work for circulating the hot water in the circulating flow path. In the conventional hot water supplying apparatus as described above, temperature of hot water is maintained at a prescribed level by adjusting a flow rate in the temperature insulating/adjusting valve 13, and hot water can instantly be directed into the load member 15. However, as the heat exchangers 11'-1,2,3 are located away from the circulation pump 7 by degrees, the pipe resistance becomes larger and larger, and a flow rate of hot water through the heat exchangers decreases proportionately. (1) If temperature of hot water flowing along the flow generating path 3 including the heat sensor 12-3 attached to the heat exchanger 11'-3 of the minimum flux becomes lower due to natural heat emission to outside of the pipe because of the extreme lowering of the flowing speed, the heat sensor 12-3 outputs a signal irrespective of the fact that temperature of heated water inside the heating can 18 is not too low, and operation of the heater 10 is unnecessary. (2) When a flow rate in the heat exchanger 22 becomes lower, hot water moves nearer to an entrance of the heat exchanger 22 as indicated by a dotted line arrow in Fig. 8 due to the water supplied from the water supply section 21 into the heating can 18 and the hot water circulating by convection, and the hot water inside the flow generating path 3 flows in the reverse direction, whereupon the heat sensor 12-3 outputs a signal. The signal generated by the heat sensor 12-3 is inputted into the heater 10, and the heater 10 is actuated. Consequently, the temperature of the hot water in the heating can 18 becomes abnormally high, which may cause damages to the heat exchanger 11'-3. Besides, it causes idling and troubles in the circulation pump 7, and for this reason sometimes the high limit sensor may make a decision that the temperature is abnormally high, and causes unnecessary shutdown of the heat exchanger 11'-3. Another known apparatus used for supplying hot water is disclosed in the document Patent Abstracts of Japan, vol. 014, No. 335 and JP-A-02 115 627. This apparatus comprises a common heater for heating water in two closed loop conduits, the first one being mounted between a reference level and a first set level higher by a pressure head than the reference level, whereas the second one is mounted between the reference level and a second set level higher by the pressure head than the first set level. The closed loop conduits are mounted in parallel and may be therefore constructed with the same specifications. Moreover, the control of the heater is simplified. SUMMARY OF THE INVENTION The present invention was made in the light of the first hot water supplying apparatus as described above, and an object thereof is to solve the problems involved in this apparatus. Thus, the flux of water flowing in the flow generating path is not limited to a minimum flow rate, no damage is given to the heat exchanger because temperature of the hot water in the heating can does not go abnormally high, and there is no need for stopping operation of the heat exchanger, which avoids unnecessary stopping, so that no trouble is generated due to idling of the circulation pump. Further embodiments according to the invention provide a hot water supplying apparatus having the following characteristics. While combustion gas generated in the combustion chamber after actuation of the heat exchanger, goes up in the heating chamber and then goes down and is exhausted from the exhaust port to outside, heat exchange is performed between the combustion gas and the water in the heating can installed on the external surface of the heating chamber, the combustion gas gives its heat to the water through this heat exchange, the downward flowability becomes higher thereupon the combustion efficiency raised and incomplete combustion prevented, and also the liquid in the heating can generates convection and goes up and down in the heating can. Thus, the heat exchange efficiency between the combustion gas and the liquid is improved and the temperature of the liquid is raised within a short period of time. In order to achieve the objects as described above, the present invention provides a hot water supplying apparatus including a hot water generating section having a hot water generating flow path, a load section having a load flow path and a branch flow path, and a connection flow path having a circulation pump therein and connecting said hot water generating flow path to said load flow path, wherein said hot water generating section comprises heat exchangers provided in the hot water generating flow path, each heat exchanger having a heater and a heat sensor controlling the operation of the heater, said load flow path comprises a temperature insulating/adjusting valve, said branch flow path comprises a load member and connects the upstream side of said temperature insulating/adjusting valve to the downstream side thereof, and said connection flow path comprises furthermore a bypass flow path having a flux control valve connecting the upstream side of said heat exchangers to the downstream side thereof. Also, the present invention provides a hot water supplying apparatus wherein each heat exchanger comprises inside a heating chamber which has a flame supply port of the heater and is placed in the lower section of said heat exchanger in one side thereof, an exhaust port provided in the lower section of said heat exchanger in another side thereof, and an intermediate portion which connects said flame supply port with said exhaust port and has an inverted U-shaped form. Furthermore, the present invention provides a hot water supplying apparatus wherein said flame supply port is located above the exhaust port and is sealed by the heater. In the hot water supplying apparatus according to the present invention as described above, after the temperature insulating/adjusting valve is fully opened and the entire circulating flow path including the bypass flow path is completely filled with water, the circulation pump is actuated to circulate water in the circulating flow path, and at the same time the heat exchanger is actuated to heat water. When temperature of the water heated as described above goes up to a prescribed level, the temperature insulating/adjusting valve is opened to a prescribed angle so that the pressure difference between hot water before and after the temperature insulating/adjusting valve as well as temperature therein indicate a minimum flux previously prescribed, and when temperature of the water in the flow generating path goes down below the prescribed level, the heat exchanger is actuated to heat water. On the contrary, when temperature of the water in the flow generating path becomes higher than the prescribed level, operation of the heat exchanger is stopped, thus the operation for heating water being stopped. During these steps, the circulation pump is always working so as to circulate hot water between outward flow paths and inward flow paths as well as to make hot water flow through the bypass flow path, and with these operations flux of hot water flowing into the heat exchanger in the hot water generating section is increased. In this step, when the heater in the heat exchanger is actuated, combustion gas generated in the heating chamber goes up and then goes down in the heating chamber and is exhausted via the exhaust port through the exhaust pipe to the outside. Thus, during the period when the combustion gas goes up and goes down in the heating chamber, heat exchange is performed between the combustion gas and the liquid in the heating can on the external surface of the heating chamber, and because of this heat exchange, the combustion gas especially in the downflow section supplies heat to the liquid inside and outside thereof, the downflow flowability being raised. During this step, the liquid in the heating can generates convection, going up and down in the heating can, so that the heat exchange efficiency between the combustion gas and the liquid is raised. Furthermore, the combustion gas stays inside the heat exchanger even when operation of the heat exchanger is down, which prevents permeation of cool air from outside. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig.1 is a piping diagram illustrating an embodiment of the present invention; Fig.2 is a vertical cross sectional view illustrating a portion of the hot water generating section in the embodiment shown in Figure 1; Fig.3 is a diagram illustrating the state of heat exchange generated by the combustion gas in the heating chamber of the embodiment shown in Figure 1; Fig.4 is a vertical cross sectional view illustrating a portion of the hot water generating section in another embodiment; Fig.5 is a vertical cross sectional view illustrating another embodiment of the present invention; Fig.6 is a diagram illustrating the state of heat exchange generated by the combustion gas in the heating chamber of the embodiment shown in Figure 5; Fig.7 is a piping diagram illustrating a conventional hot water supplying apparatus constituting the prior art of the present invention; and Fig.8 is a vertical cross sectional view illustrating a portion of the hot water generating section of the conventional apparatus shown in Figure 7. DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiment of the present invention shown in Fig.1 and Fig.2 has, in most portions thereof, almost the same configuration as that of the conventional hot water supplying apparatus as described above, so that the same reference numerals are assigned to such portions, the description of which is omitted herein, and description is made mainly for the different portions. Between the outward flow path 5 and the inward flow path 6 is provided a bypass flow path 8 having a flux control valve 9 connecting with the upstream side from the heat exchangers 11-1,2,3 to the downstream side therefrom. Furthermore, inside the heating can 18 of the heat exchangers 11-1,2,3 the heater 10 has a flame supply port opened in the lower section in one side of the heating can, while the exhaust port 24 is provided in the lower section in another side thereof, and the intermediate section between the flame support port and the exhaust port has an inverted U-shaped form to form the heating chamber 19. In the hot water supply apparatus as described above, like in the conventional apparatus, after the temperature insulating/adjusting valve 13 is fully opened and the entire circulating flow path is completely filled with water, the circulation pump 7 is actuated to circulate water in the circulating flow path, while the heat exchangers 11-1,2,3 are actuated to heat water, and when temperature of the water heated as described above goes up to a prescribed level, the temperature insulating/adjusting valve 13 is opened to a prescribed angle, which creates a pressure difference of the hot water before and after the valve 13, and temperature in the temperature insulating/adjusting valve 13 indicates a prescribed minimum flow rate. Thus, when the temperature of the water, in the flow generating path 3 becomes lower than the prescribed level, the heat exchangers 11-1,2,3 are actuated to heat water, and on the contrary when the temperature of the water, in the flow generating path 3 becomes higher than the prescribed level, operation of the heat exchangers 11-1,2,3 are stopped, which stops the operation for heating water. During these steps, the circulation pump 7 is always working to circulate hot water through the outward flow path 5 and inward flow path 6 and also through the bypass flow path 8. Thus, with this operation, flux of water flown into the hot water generating section 1 increases, which in turn makes it possible to prevent heated water in the heating cans from being heated to an abnormal high degree due to shortage of the flux. For this reason, there is no possibility that any damage is given to the heat exchangers, the necessity to stop operation of the heat exchangers is eliminated when it is unnecessary, and also troubles due to idling of the circulation pump is prevented. If the heater 10 of the heat exchanger 11 shown in Fig.2 is actuated in the step described above, combustion gas generated in the heating chamber 19 goes up through the upflow section 41, enters the upper distribution section 43, then turns around and goes down through the downflow section 42, and is exhausted via the exhaust port 24 through the exhaust pipe to the outside. The heat exchanger proposed by the present applicant and disclosed in Japanese Utility Model No.55-42216 is similar to the heat exchanger 11, but in this type of heat exchanger, a phenomenon called up/down flow of combustion gas occurs, so that description is made below for this phenomenon referring to Fig.3. It is known that combustion gas generated after actuation of the heater 10 generates the internal aeration force Pch shown by the following equations (1) and (2) irrespective of the state of peripheral air in a gas combustion path having the upflow section 41 as well as the down-flow section 42, height H being the same as that of the upflow section 41 in the heating chamber 19: Pch = (γd - γu). H Pch = PH/R (1/Td - 1/Tu) wherein γd: Specific weight of combustion gas in the downflow section 42 γu: Specific weight of combustion gas in the upflow section 41 H: Height from the heat generating point U to the middle point M P: Pressure of combustion gas R: Combustion gas constant Td: Temperature of combustion gas in the downflow section 42 Tu: Combustion gas temperature in the upflow gas section 41. When the heat exchanger 11 is working, in other words when the heater 10 is working, always the relation of Tu > Td is satisfied, so that (1/Td - 1/Tu) > 0, and the combustion gas flows from the heat generating point U to the middle point M and then to the exhaust point D. In contrast to it, when operation of the heat exchanger 11 is down, Tu is equal to Td as well as to temperature of the peripheral water, and for this reason the internal aeration force Pch becomes 0 (zero) with the combustion gas flow in the combustion gas flow path stopped, which prevents permeation of cool air from outside to maintain the internal temperature. Fig.4 and Fig.5 show 2 other examples of the heat exchanger 11 (called Example 2 and Example 3 respectively). In these examples, as the exhaust point D is located at a position lower by h than the heat generating point because of the architecture in which the hot water supplying point is installed as shown in Fig.6, the exhaust point D is located at a position by h lower than the heat generating point U as shown in Fig. 6. For this reason, pressure at points U,M and D being Pu,Pm, and Pd respectively, the following equations are provided: Pd = Pm + ∫ γd.dh Pu = Pm + ∫ γu.dH = Pm + γu.H wherein Pd is released to the atmosphere, so that Pd is equal to Po (Atmospheric pressure). Accordingly, the following equations are also provided: Po = Pm + γd.H + γd.h Pm = Po - γd.H - γd.h By substituting equations (5) and (6) into equation (4), the following equation is obtained: Pu = Po - γd.H -γd.h + γu.H = Po - γd.h Herein, when operation of the heat exchanger 11 is down, γd is equal to γu, so that Pu = Po - y d.h, namely Pu - Po = - γd.h < 0. For this reason, the relation of Pu < Po is always satisfied, and the combustion gas in the combustion gas flow path always flows from the exhaust point D to the middle point M and then to the heat generating point U without staying in the combustion gas flow path. Therefore, permeation of external air cannot be prevented and heat of hot water in the heating can 18 is disadvantageously emitted to outside. In other words, when operation of the heater 10 is stopped, theoretically the internal combustion gas tries to flow from the exhaust point D to the middle point M and then to the heat generating point U, namely in the direction contrary to that when the heat exchanger 11 is working, for going out of the apparatus, like in the conventional type of hot water supplying apparatus. In these 2 examples, however, the heater 10 is located at the flame supply port 23 to prevent gas distribution therethrough, so that the combustion gas stagnates inside the heating chamber 19, which prevents permeation of external cool air and maintains the internal temperature. Thus, heat of hot water in the heating can 18 is emitted to outside. It should be noted that, in Example 3, the downflow section 42 is located outside the heating can 18 and this downflow section 42 is covered by a heat insulating material 44. The present invention is as described above, and in the hot water supplying apparatus according to Claim 1, a flow generating path 3 in a heat generating section 1 is connected with a load flow path 4 in a load section 2 with a connection flow path, a circulating flow path having a circulation pump 7 therein is formed by these flow paths, heat exchangers 11-1,2,3 each having a heater 10 therein and a heat sensor 12 provided in flow generating path 3 and controlling operation of the heaters 10 are provided in the hot water generating section 1, a temperature insulating/adjusting valve 13 is provided in the load flow path 4, a branch flow path 14 connected with the upstream side of the temperature insulating/adjusting valve 13 and the downstream side thereof is provided in load flow path 4, a load member 15 is provided in this branch flow path, and a bypass pipe 8 having a flow rate control valve 9 and connected with the upstream side of the heat exchangers and the downstream side therefrom is provided in the connection flow path, so that flux of water flowing in flow generating path 3 is not limited to the minimum flux and any damage due to abnormally high temperature of hot water in the heating can 18 is not caused to the heat exchanger. Therefore, the necessity of stopping operation of the heat exchanger is eliminated when it is not required, and also troubles due to idling of the circulation pump can be prevented. In addition to the features disclosed in claim 1, the features disclosed in claims 2 and 3 provide the following merits: while combustion gas generated in the combustion chamber after actuation of the heat exchangers goes up and then goes down in the heating chamber and is exhausted from the exhaust port to the outside, heat exchange is performed between the combustion gas and water in the heating can on the external surface of the heating chamber, the combustion gas in the heating chamber supplies heat to water outside thereof through heat exchange, so that the downward flowability is improved, while the combustion efficiency is raised and incomplete combustion prevented; connections movement created in the water out of the heating chamber raises the heat exchange efficiency between the combustion gas and water so that the temperature of the water raises quickly; even when operation of the heat exchangers is stopped and the combustion gas tries to flow outward, the combustion apparatus provided in the flame supply port prevents distribution of the combustion gas, and the combustion gas stays inside the heat exchanger, which prevents permeation of cool air from outside and maintains the internal temperature at a constant level.

Claims: A hot water supplying apparatus including a hot water generating section (1) having a hot water generating flow path (3), a load section (2) having a load flow path (4) and a branch flow path (14), and a connection flow path (5,6) having a circulation pump (7) therein and connecting said hot water generating flow path (3) to said load flow path (4), wherein said hot water generating section (1) comprises heat exchangers (11) provided in the hot water generating flow path (3), each heat exchanger (11) having a heater (10) and a heat sensor (12) controlling the operation of the heater (10), said load flow path (4) comprises a temperature insulating/adjusting valve (13), said branch flow path (14) comprises a load member (15) and connects the upstream side of said temperature insulating/adjusting valve (13) to the downstream side thereof, and said connection flow path (5,6) comprises furthermore a bypass flow path (8) having a flux control valve (9) connecting the upstream side of said heat exchangers (11) to the downstream side thereof. A hot water supplying apparatus according to claim 1, wherein each heat exchanger (11) comprises inside a heating chamber (19) which has a flame supply port (23) of the heater (10) and is placed in the lower section of said heat exchanger (11) in one side thereof, an exhaust port (24) provided in the lower section of said heat exchanger (11) in another side thereof, and an intermediate portion which connects said flame supply port (23) with said exhaust port (24) and has an inverted U-shaped form. A hot water supplying apparatus according to claim 2, wherein said flame supply port (23) is located above the exhaust port (24) and is sealed by the heater (10).

Inventors: MARUYAMA NOBORU, MARUYAMA, NOBORU
Applicants: MARUYAMA NOBORU, MARUYAMA, NOBORU
Application year: 1994
Main classification: F24D17
IPC codes: F24H1, F24D17